Organizations and Communities can have any number of pages defined within them. Pages are organized into Layouts, and there are two types of Layouts: Public and Private. User Groups don't have pages per sé, but rather can have Page Templates. By default, each user gets a personal community, which itself has public and private layouts. This is a personal web site which the end user can configure.

Roles can be created under one of two scopes: Portal Role and Community/Organization Role.

Portlets could be either non-instanceable or instanceable. Non-instanceable portlet (e.g. wiki portlet) has its data scoped by the community or organization to which it belongs. No matter how many times you add it to a page with the community or organization, it will point to the same data. On other hand, in case of instanceable portlets (e.g. RSS portlet), since many of them can be placed on the same pages in any community or organization, they all have their own sets of data.

Liferay's Control Panel is the central location where just about everything can be administered.

While designing the portal, first step is to get answers to following questions:

Will users be given freedom to sign up on the site?

Will your user groupings be ad-hoc, static, or both? (If your user groupings will be ad-hoc, you know you'll be creating communities for your users to join and leave.)

Will some regular users have access to things others won't? (If so, you know you'll be using Roles.)

Will you be delegating administrative tasks to some users? (If so, you may have Community or Organization Administrators.)